The sidewise turnover of vehicles when driving curves depends on the cornering force which is exerted by the wheels of the vehicle. Therefore, in order to prevent a sideways turnover, the cornering force has to be reduced in an appropriate manner. Known systems for increasing the turnover stability use the following effects for this purpose:                Reduction of the tyre cornering force by reducing the vehicle speed        Reduction of the tyre cornering force by blocking the wheel        Reduction of the tyre cornering force by intervention into the steering angle of the vehicle.        
The present invention deals with a method for increasing the sideways turnover security when driving curves of rear wheel steered vehicles by an intervention into the steering angle.
From DE 100 08 984 A1 it has become known to make the steering movement of industrial trucks dependent from the mass and/or the lifting height of a load that is taken up by the industrial truck. In this it is dealt with a controlled method without making use of driving dynamic variables of the vehicle. Any intervention into the steering angle is not provided.
From DE 199 18 597 C2 it has become known to perform an automatic steering intervention after determination of a so-called turnover coefficient. However, a steering intervention according to this method makes sense only for vehicles with front wheel steering. The particular properties of rear wheel steered vehicles are not taken into account. Moreover, several additional sensors are necessary on the vehicle.
From DE 195 15 053 A1 it is known to detect slip angles for the front and rear wheels, and to construe a slip angle difference as a control variable. The slip angles on the front and rear wheels are detected through the sideslip angle and the yaw rate. With the aid of the known method, oversteering or understeering of the vehicle can be influenced. However, an enhancement of the dynamic turnover security of rear wheel steered vehicles is not possible with the known method.
The present invention is based on the objective to provide a method for the prevention of turnover of rear wheel steered vehicles, which takes sufficiently into account the driving dynamic behaviour of such a vehicle when driving in curves.